Properly detect active password manager by calling getSettings (which…

… has the logic to default if not set).

Previous code would fail for anyone who had a session before PW manager was simplified down to a single choice, because they did not have ACTIVE_PASSWORD_MANAGER set.

Auditors: @dandart

Fixes #3516

js/state/contentSettings.js

@@ -12,6 +12,7 @@ const {passwordManagers, defaultPasswordManager} = require('../constants/passwor
 const urlParse = require('url').parse
 const siteSettings = require('./siteSettings')
 const { registerUserPrefs } = require('./userPrefs')
+const { getSetting } = require('../settings')
 
 // backward compatibility with appState siteSettings
 const parseSiteSettingsPattern = (pattern) => {
@@ -32,7 +33,7 @@ const addContentSettings = (settingList, hostPattern, secondaryPattern = undefin
 const getPasswordManagerEnabled = (appState) => {
   let appSettings = appState.get('settings')
   if (appSettings) {
-    const passwordManager = appSettings.get(settings.ACTIVE_PASSWORD_MANAGER)
+    const passwordManager = getSetting(settings.ACTIVE_PASSWORD_MANAGER, appSettings)
     if (typeof passwordManager === 'string') {
       return passwordManager === passwordManagers.BUILT_IN
     }